The document discusses the greenhouse effects on other planets and how they compare to Earth. Mars has a thin atmosphere composed primarily of carbon dioxide that produces a greenhouse effect raising the surface temperature by only 10 degrees Celsius, making it too cold for life. Venus has a dense carbon dioxide-rich atmosphere that causes a runaway greenhouse effect, raising the surface temperature over 500 degrees Celsius, making it too hot for life. In contrast, Earth's atmosphere and levels of carbon dioxide and water vapor produce a greenhouse effect that moderately raises the surface temperature by 33 degrees Celsius, providing conditions suitable for life.